1. Field of the Invention
The invention relates in general to a method for generating three-dimensional image content, and more particularly to an example-based two-dimensional to three-dimensional image conversion method, and an image conversion system.
2. Description of the Related Art
As the computer technology is developed rapidly, three-dimensional (3D) modularized software and animation software products are increasingly available in the industry. For example, one can use TrueSpace, 3D Studio Max, AutoCAD R14, 3D Webmaster, Live Picture, Division, or Sense 8 WTK R6. These software programs share some features in common. For example, they may complete the model, image processing, sound effect recording and the whole 3D layout integrating at the same time; they may provide some layout examples, objects, sound effects and materials which the user can make use of or modify so as to reduce lead-time; they may improve the interaction among objects in the virtual layout so as to make the 3D environment approximate to the real world. From the development and features of these software programs, it can be seen that the way for generating the 3D content is an important issue in the 3D industry.
On the other hand, a stereoscopic display capable of simulating the 3D stereoscopic visual effect has also been commercialized. Conventionally, according to the principle that the distance between two eyes (left and right eyes) of the human being forms different focuses which cause depth perception for the brain, the stereoscopic display provides different images for the two eyes of a viewer so as to make the viewer percept a multifocal image and achieve the purpose of 3D displaying. In this case, in order to percept the 3D image effect, the viewer needs to wear a pair of dedicated eyeglasses. In addition, there is a flat panel display, such as a liquid crystal display, a plasma display panel, or a projection stereoscopic display, which enables the user to acquire the 3D visual effect by casting multi-view images without the need of wearing the dedicated eyeglasses. For example, Philips presents a stereoscopic display based on the 3D display technology (referred to as WOWvx). Theoretically, using a 2D image with corresponding depth information, i.e., an original 2D image (color image) with a depth map corresponding to the 2D image, a stereoscopic image with at least two different viewing angles for left and right eyes can be obtained by way of simulation, or through the displaying of a multi-view stereoscopic display.
However, the popularization and application field of the stereoscopic display have been limited for lack of the 3D content that the stereoscopic display can utilize. Thus, in academic and professional practice, it is an important subject to generate a 3D content quickly and conveniently so that the stereoscopic display can output a 3D image by using the 3D content.
Because the image content is mainly based on the 2D image in the current information environment, it will be shown in the following that how the 2D image can be converted into the 3D content by the prior artisan.
In a conventional 2D/3D image converting technique, the method began with searching all the objects' edges in a whole 2D image, and then determined the objects in the order from front to rear by way of analysis of the color contrast thereof. This method was preferably applied to an image without significant segregation among the objects, such as a landscape scenery image. However, if the 2D image obviously had a number of objects such as people, cars, and buildings, while the objects of people and cars may not be defined, an error may occur in depth prediction.
In addition, Dynamic Digital Depth (DDD) in the United States presented a 3D software tool. The method thereof mainly relies on one's manual computer operations to add and modify the edge and depth relation of different objects in a 2D image. If the depth prediction generated automatically by software had the disappointing result, further modification by the manual operation is usually required to meet the needs. This is time consuming.
Further, Philips presented a software tool referred to as Bluebox, which provides user interfaces so that the user may convert the video content into the 3D content by way of manual-oriented semi-automatic operation.
Concerning to the depth prediction to generate 3D content, the above prior art may be limited to some specific types of 2D image content, or may be relied on modification by the manual operation.